The field of use of a drive unit of this type with a drive motor and a planetary gear mechanism extends principally to drive transmissions, winching gear mechanisms and swiveling gear mechanisms and to stationary gear units or else pitch and azimuth gear mechanisms for wind power plants.
As a rule, the planetary gear mechanism in drive transmissions and swiveling gear mechanisms is provided to step down the rotational speed of the drive motor. The at least two planetary stages of the planetary gear mechanism transmit the converted torque to a single-piece internal gear or a plurality of internal gears which are connected to one another and are integrated into a hub housing. The configuration of the planetary gear mechanism and of the internal gears which are integrated into the hub housing is to be adapted for the respectively required torque. The toothing systems of the internal gears are therefore produced individually by way of butt joining or reaming. The advantages of said drive unit lie, in particular, in the compactness of the arrangement. The disadvantage is to be seen in the wide variety of parts. The butt jointed or reamed toothing system of the internal gears changes depending on the transmission ratio and causes a completely new internal gear variant. The customer-specific differentiation already takes place at the blank part level at a very early time in the value chain. This leads firstly to high costs and, moreover, has a massive influence on the delivery capability, the delivery reliability and the logistics concept. A standardized planetary gear mechanism and a hub housing with a standardized internal gear represent a development of said drive unit.
A switchable hydrostatic compact drive is apparent from document EP 1 761 718 B1, with at least one planetary stage, in which a first switchable multiple disk clutch connects an internal gear fixedly to a housing so as to rotate with it, and in which a second switchable multiple disk clutch connects the sun gear of the planetary gears fixedly to the internal gear so as to rotate with it. The sun gear of the planetary stage is driven by a hydraulic motor and a planet spider of the planetary stage is provided as output. For use as a traction drive or winching drive, the stationary housing which is arranged on the outside is provided with a hub housing which serves as output and is arranged rotatably with respect to the former. The tapered roller bearing system which is arranged between the housing and the hub housing absorbs the forces which act on the gear mechanism from the outside. In the inner region of the housing, an annular disk carrier receives the inner disks of the first multiple disk clutch radially on the outside and, lying opposite them radially on the inside, the outer disks of the second multiple disk clutch and a spring store which is arranged axially next to them and acts on the disk carrier in the axial direction in order to close the second multiple disk clutch. When the second multiple disk clutch is closed, the axial force of the spring store is supported on one side on said disk carrier, the multiple disk assembly being supported in turn on the disk carrier, furthermore. At least one further planetary stage for stepping down the gear mechanism rotational speed is connected downstream of the planet spider of the planetary stage. The planetary stages which are connected downstream of the planet spider transmit the converted torque via in each case one internal gear to the hub housing.
In a first gear, the multiple disk assembly of the first multiple disk clutch is pressed together by way of a spring store. As a result, the internal gear with the disk carrier which is connected in a rotationally fixed manner is connected via a further disk carrier to the housing. The input rotational speed is transmitted by the sun gear via the planetary gear and the planet spider with a transmission ratio i>1 to the planetary gear mechanism. In a second gear, the step piston is loaded with pressure and releases the rotationally fixed connection of the disk carriers. The internal gear can rotate freely with respect to the housing. In this switching state, the planetary gear is blocked per se via the connection of the sun gear and the internal gear and forwards the input rotational speed with the transmission ratio i=1 to the planetary stage.
On account of the switchable preliminary gear stage, this configuration of the drive unit with a switchable preliminary gear stage permits a standardized planetary gear mechanism and hub housing. However, the switchable preliminary gear stage is of relatively complex configuration and comprises a large number of components, as a result of which it is relatively expensive to produce. In addition, the preliminary gear stage takes up installation space and increases the weight of the entire drive unit.